Serum Levels of TRAP5b, a New Bone Resorption Marker Unaffected by Renal Dysfunction, as a Useful Marker of Cortical Bone Loss in Hemodialysis Patients

Abstract

Tartrate-resistant acid phosphatase (TRAP) 5b is a new marker of bone resorption that is unaffected by renal dysfunction. The significance of TRAP5b was assessed in hemodialysis (HD) patients. Serum concentrations of TRAP5b and cross-linked N-telopeptide of type I collagen (NTX) were determined as bone resorption markers, and those of bone alkaline phosphatase (BAP) and intact osteocalcin (OC) were measured as bone formation markers in 58 HD patients. Bone mineral density (BMD) was measured by dual-energy X-ray absorptiometry twice in the distal third of the radius, with a 2-year interval between measurements. Serum TRAP5b correlated significantly with BAP, intact OC, intact parathyroid hormone (PTH), and especially serum NTX. TRAP5b, NTX, BAP, and intact OC all correlated significantly with BMD at the time of the second measurement; and TRAP5b, NTX, and intact OC, but not BAP and intact PTH, correlated significantly with the annual change in BMD during the 2-year period. Among the bone markers, patients in the highest tertile for serum TRAP5b and intact OC showed the fastest rate of cortical bone loss. The sensitivity and specificity for detection of rapid bone loss were 57.9% and 76.9%, respectively, for serum TRAP5b. Measurement of serum TRAP5b, as well as intact OC, may be a clinically relevant assay for estimation of bone metabolic status in HD patients, although serum intact OC accumulates in uremic serum.

Effect of zinc supplementation on bone formation in hemodialysis patients with normal or low turnover bone

“…Serum TRACP5b increased transiently to 368 (161-807) at 12 months (Table 2), although no change in serum intact PTH was observed in this study. The mechanism of increase in TRACP5b at 12 months was unknown, but serum TRACP5b at 12 months was comparable with the previous report 20 indicating that annual cortical bone loss in the distal third of radius was not observed except for the highest tertile of HD patients including female with TRACP5b of 490 ± 320 mU/dL, and Zn administration has been shown to decrease osteoclastogenesis in Zn adequate rats. 21 Therefore, it is suggested that Zn supplementation might not cause bone mineral reduction in spite of the transient increase in serum TRACP5 at 12 months.…”

FGF-23, α-Klotho Gene Polymorphism and Their Relationship with the Markers of Bone Metabolism in Chronic Peritoneal Dialysis Patients

“…Among several known metabolic bone markers, serum levels of procollagen I amino-terminal propeptide, bone alkaline phosphatase and TRAP5b were reported not to be affected by renal dysfunction and accumulation due to impaired excretion [19]. Our results have shown a strong correlation among iPTH levels and serum concentrations of BAP and PINP and hence confirmed this opinion with the exception of TRAP5b.…”

“…Therefore, in peritoneal dialysis patients, any diagnostic value for osteoprotegerin levels during the course of CKD-MBD may seem questionable. Beta CTx, an osteoclastic bone resorption marker, has been reported to increase during the course of secondary hyperparathyroidism, but also reported to accumulate due to impaired excretion into the urine [19]. Our results have shown that, PD patients had significantly higher serum concentrations of beta CTx compared to normal subjects.…”

The Assessment of Fracture Risk

“…The bone-remodeling process is therefore shifted toward bone resorption, resulting in an imbalance of bone turnover that causes osteoporosis. High-turnover osteoporosis is the most common form and occurs in postmenopausal women (so-called primary type-I osteoporosis) or in patients with hyperparathyroidism regardless of their menopausal state 48 . Transient osteoporosis, most commonly seen in men, is also a high-turnover state 49 .…”